The present invention relates to a soft fibrous sheet suitably used as a shock absorbing member for packing, building or the like. A fibrous material of an inorganic fiber or of a vegetable fiber such as wood pulp, waste paper or the like is used as a raw material.
It has been common, heretofore, to manufacture this kind of soft fibrous pulp sheet by a wet type process using water as a medium with the fibrous raw material soaked in water. This process, however, is defective in that, for maintaining the shock absorbing property of the resulting fibrous pulp sheet, large-scale apparatus is needed for sucking up the water and for forming and drying, so that the process has high cost of equipment. In a manufacturing process of a soft fibrous sheet by a conventional dry type process, it is usual that fibrous and an adhesive agent are first mixed, and the mixture is then formed into an uniform thickness sheet layer to be heated and compressed. This is defective, however, in that the fibers are liable to become entangled in a lump by the action of the adhesive agent. A uniform and good quality sheet in which the fibers are loosened, cannot be thereby obtained.
Accordingly, in view of those defects in the conventional process, the principal object of the present invention is to provide a soft fibrous sheet manufacturing process in which a good quality of pulp sheet with fibers uniformly dispersed is obtained. It is also an object of the present invention that after a crushed fibers sheet layer of large width and uniform thickness is formed by dispersion of finely crushed fibers, the crushed fibers sheet layer is impregnated with an adhesive agent and is then heated and compressed.
Another object of this invention is to provide a manufacturing process of a soft fibrous sheet having an excellent shock absorbing property. The crushed fibers sheet layer impregnated with the adhesive agent, is heated and compressed by a heating and compressing member having its concave-convex surface so that a large number of shock absorbing projections are formed, by embossing, on its surface.
Another object of this invention is to provide a manufacturing process of a soft fibrous sheet which is very smooth, and in which the crushed fibers sheet layer impregnated with the adhesive agent is laminated at least at its one side surface with a thin sheet member such as a sheet of thin paper, thin cloth or the like. The sheet layer is heated and compressed through the thin sheet member.
Another object of this invention is to provide a soft fibrous sheet formed of very homogeneous crushed fibers. The soft fibrous sheet is to be especially excellent in shock absorbing property, and have improved mechanical strength.
Another object of this invention is to provide manufacturing apparatus for a fibrous sheet formed of crushed fibers uniformly dispersed as described above. The apparatus comprises crushing means for crushing fibers, loosening means for dispersing the crushed fibers, conveying means for conveying the crushed fibers as a continuous and uniform thickness belt form of sheet layer, adhesive agent spraying means for applying uniformly an adhesive agent to the crushed fibers sheet layer, and heating and compressing means for heating and compressing the crushed fibers sheet layer impregnated with the adhesive agent.
Another object of this invention to provide manufacturing apparatus for a soft fibrous sheet especially excellent in shock absorbing property, and having heating and compressing means in the form of a heating and compressing surface member having on its periphery a large number of recesses and a compressing member for pressing thereagainst the crushed fibers sheet layer impregnated with the adhesive agent.
Another object of this invention is to provide manufacturing apparatus for a soft fibrous sheet high in strength and flexibility. The apparatus includes thin sheet supplying means for supplying a thin sheet member such as a sheet of thin paper, thin cloth or the like onto the crushed fibers sheet layer impregnated with the adhesive agent.
The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.